Diabetes is associated with serious cardiovascular complications that include atherosclerotic coronary artery disease and myocardial dysfunction even in the absence of underlying coronary artery disease, a disorder termed diabetic cardiomyopathy (DCM). Data from studies of animal models and human subjects provide evidence that alterations in myocardial lipid metabolism is central to the pathogenesis of DCM, which early on can be asymptomatic, but which can progress to symptomatic heart failure. The ability to identify new disease markers to facilitate early detection and intervention is limited b inadequacies of existing measures of systemic and myocardial lipid metabolism in humans. In our Preliminary Studies, we have addressed this problem by using sensitive mass spectrometry-based metabolomics to identify two plasma very long-chain ceramides, Cer(22:0) and Cer(24:0), that are highly correlated with asymptomatic systolic dysfunction in obese and type 2 diabetic humans. Cell biological and mouse model studies suggest these species arise from the unique intersection of ectopic lipid accumulation and activation of innate immune signaling pathways. We hypothesize that plasma Cer(22:0) and Cer(24:0) reflect systemic alterations in lipid metabolism that can be exploited as novel biomarkers for DCM. While the diagnosis of cardiac dysfunction can be readily made noninvasively by echocardiogram, Cer(22:0) and Cer(24:0) track with pathophysiological consequences of ectopic lipid accumulation and thus have potential to predict individuals at risk, to further our understanding of disease mechanism, and to identify new treatment targets. We have assembled a multidisciplinary team to extend these findings by 1) Developing a robust high-throughput clinical assay for Cer(22:0) and Cer(24:0); 2) Validating and extending these findings in two existing cohorts of human subjects; 3) Exploring the mechanistic links between very long-chain ceramides and cardiac dysfunction in relevant mouse models of DCM; and 4) Defining the direction of causality in the relationships among lipid exposure, plasma ceramides, and cardiac function in humans with type 2 diabetes. Our approach has the potential to define an integrated measure of pathophysiologically relevant lipid exposure that can be used to track intervention success, data linking phenotype to a modifiable risk factor that is currently undertreated in the target population (dyslipidemia), and marker for future disease risk that can be acted upon to prevent clinically apparent morbidity and mortality.